Laserfiche WebLink
improvements in capabilities of the mining equipment planned for the Dove Gulch area <br />(Stewart 2005). <br />5.3 Surface Deformation <br />Figure 14 presents surface subsidence over the analyzed four longwall panel block, <br />Upper B Seam, Dove Gulch. Predicted maximum subsidence is 9 ft within the longwall <br />panel areas. It approaches 4 ft over the deeper gateroads. Based on similarities in <br />geologic and mining plans for the Upper D and Upper B seam longwall blocks, surface <br />movement in Dove Gulch are expected to be similar to that experienced in the D1-D9 <br />panel areas. Maximum subsidence is expected to be 15% higher as influenced by the <br />higher extraction height presently planned for Dove Gulch. <br />Predicted tensile strains along two east-west cross sections of interest (AA' and BB' <br />passing through two sets of springs) are presented in figures 15 and 16, respectively. In <br />these figures, we have presented horizontal strain patterns while accounting for variations <br />. in topographic and mining conditions. Figure 15 clearly shows final compression within <br />the center of the panels and tension near the gate pillars. Tensile strains are significantly <br />reduced at location BB' under deeper cover. Surface strains are generally higher at lower <br />elevations. This indicates a greater potential for surface fracturing over shallow cover to <br />the east of the reserve near B8 panel. Some fracturing is also possible at higher <br />topographies as indicated by regional experience. <br />Using a criterion suggested by Singh and Bhattacharya (1984), calculated strains <br />reach levels that may cause surface fractures (figures 15 and 16). Fracturing is more <br />likely to occur over panel boundaries and gate roads, particularly to the east under <br />shallow cover. Many of the fractures forming in front of the face should heal due to <br />compression and settling of the surface, but some of the fractures in tensile zones over the <br />gate roads and near panel boundaries may remain open. Subsequent movements over the <br />gateroads caused by long-term pillar failure may reduce strain and heal some of the <br />fractures formed above the gateroads. <br />Maleki Technologies, Inc. Page 32 <br />